A335908 Average of those twin prime pairs p, q=p+2, for which A335884(p+1) >= A335884(p-1) and A335884(q-1) >= A335884(q+1).

6, 18, 30, 42, 102, 138, 150, 198, 270, 282, 462, 522, 570, 618, 642, 810, 822, 858, 882, 1050, 1062, 1230, 1278, 1290, 1302, 1482, 1698, 1722, 1878, 1950, 1998, 2082, 2130, 2142, 2238, 2310, 2382, 2550, 2658, 2730, 2790, 2802, 2970, 3258, 3300, 3330, 3390, 3462, 3558, 3582, 3822, 3918, 3930, 4002, 4050, 4158, 4218, 4230, 4242

Offset: 1

Author

Antti Karttunen, Jul 01 2020

Keywords

• nonn

Comments

For such twin prime pairs p, q, A335884(p) = A335884(q) = 1 + A335884((p+q)/2).

Crossrefs

Cf. A335884.

Subsequence of A014574. Cf. also A335907.

Programs

PARI

A335884(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+max(A335884(f[k,1]-1),A335884(f[k,1]+1))))); };
isA335908(n) = (isprime(n-1)&&isprime(n+1)&&(A335884(n)>=A335884(n-2))&&(A335884(n)>=A335884(n+2)));